Means for minimizing inductive interference.



1, nf# n A 9 00 N 2 v i.f R w ma .m A A m. y jhv a, I r-. do .P s mf, v a .7 n, n n n c E scm MEANS FOR MINIMIZING INDUCTIVE -HVI'ERFFH-ENCE.

. UNITED STATES PATENT OFFICE.

CHARLES F. SCOTT, 0F NEW HAVEN,l CONNECTICUT, ASSIGNOB T0 WESTII'GHOUSR ELECTRIC AND IANUFACTUBIN G COMPANY, COBPONATION 0F PENNSYLVANIA.

. FOB IMIINIMIZING INDUCTIVE INTEBFERENCE.

speciacation or Letters Patent.V Patented Aug; 29 191 6 sppiiuon nea January 2, 19in. semi no. 17s.

To all whom it may concern.'

Be it known that I, CHARLES F.. Scofi'r, a citizen of the United States, and a resident of New Haven, in the county of New Haven and State of Connecticut, have invented a new and useful Improvement in Means for Minimizing Inductive Interference, of which the following is a specification.

My invention relates to means for minimizing and neutralizing disturbances in electrical circuits, such as intelligence-transmission circuits, which may be caused by electromagnetic induction arising from other `circuits located in proximity thereto.

More particularly, my invention relates to improvements in means for protecting telephone, telegraph and other circuits which are utilized for the transmission of intelligence, and which are under the inductive infiuences of, and may be unequally spaced throughout their length from, other circuits utilized for the transmission of power by alternating currents.

Ordinarily, by confining the return flow of trolley currents to the track of a railway system, as explained in my patent application, Serial No. 170, filed concurrently herewith and assigned to the Westinghouse Electric & Manufacturing Company, the return currents and the trolley currents may be-disposed closely adjacent to each other in order that the inductive disturbances arising from one circuit may be substantially neutralized by the inductive disturbances arising from the other circuit. However, in

many installations, 4one or more telegraph or telephone circuits may be paralleled longer or shorter distances by a plurality of trolley conductors and their associated track rails. In addition, the relative disposition of the different circuits may vary throughout, thus effecting a flow of unbalanced disturbing currents iu the telegraph or telephone circuits.

.It is often desirable to operate with two tracks connected in parallel so that they ma divide the return current between them. f

the outgoing current traverses the trolley By means of my invention, I nductively interlink all of the circuits utilized for the transmission of power currents, and I provide means also for so adjusting the relative currents flowing in the various conductors, including the earth, as to neutralize or. minimize the disturbances impressed upon adjacent telegraph or telephone circuits. Moreover, by means of my invention, the cost of protecting telegraph and telephone circuits and the'like from inductive disturbances arising from a number of powertransmission circuits disposed adjacent to the telegraph and telephone circuits, may be reduced to a low figure.

For a better understanding of the nature and scope of my invention, reference may be had to the following description and the accompanying drawing in which- Figure 1 is a diagrammatic view of a system embodying a form of my invention; Fig. 2 is a diagrammatic view of a modification of the system shown in Fig. 1, and Fig. 3 is a diagrammatic representation of a form of transformer which I desire to utilize in my system.

Referrin to Fig. 1, a source of supply 1, s own as a single-phase alternator, is connected, through one terminal, to trolley conductors 2 and'3, and, through the other terminal, to track rails 4 and 5 which are associated with the trolley conductors 2 and 3, respectively. A formers 6, the construction of which will be 4subsequently explained, are inserted at intervals along the railway stem, as shown, primary windings 7 and 8 in connected in series-circuit relationship wi the trolle 'conductors 2 and 8, and secondary windings 9 and v10 being connected to the rails 4'and 5, respectively, and across insulatin joints 11. The insulating joints 11 divi e the rails 4 and 5 into a series of track sections which are insulated from one'u'iother. An intelligence-transmission conductor 12, shown as a telegraph conductor, is disposed adja ent to the trolley conductors 2 and 3 and is, therefore, under the inductive i influences arising from the currents flowing t ie trolley conductors and their associated track railsl Consequently, the electromotive forcesimjressed upon the telegraph cirph conductor 12 may be unequally' l power i plurality of' transl cuit will vary at differentL points along lits length, and, to this end, it is essential to impress neutralizing electromotive forces thereupon which will be of such amounts and of such character as to substantially preclude the flow of unbalanced currents over long distances in the telegraph conductor 12.

As explainedin my other patent" application which I have mentioned above, the return trolley currents are confined to the track rails 4 and 5 by reason of inductivcly interlinking ,the trolley conductors and the track rails. In this manner, the return trolley currents areimaintained in close proX- imity to the trolley conductors, 'and the inducing disturbances ar-isiiig'ii'om one will besubstantially neutralized by the inducingr disturbances arising from/the other. The telegraph conductor 12, being vunequally spaced from the different power conductors, will be under varying inducing influences. In order to compensate for these unbalanced inductive disturbances, eachof the primary windings 7 and 8, and each of the secondary windings 9 and 10, maybe provided with a plurality of taps 13 by'means of which the current flow in thefvarious conductors may bc so controlled and proportioned as to iming in one trolley conductor will necessitate a return ioW` of current lin both tracks by reason of both circuits being connected to-` gether, as previously explained. By means of the taps 13, the return currents flowingv in the several tracks may be so adjusted as to j neutralize the various electromotive forces impressed at different points on 'thek telegraph conductor 12 by the trolley cur-` rents. At the same time, the windings interlinking the trolley conductors and the tracks f may be embodied in single transformers, thereby greatly decreasing the cost of installing my system, j

Ifthe conditions are known,the number of turns comprising the transformer windings may be predetermined thereby eliminating the use of taps for adjusting the number of turns in the several windings. While a proper adjustment of the relative turns of the primary and secondary windings of the ,transformer -6 may be suiiicient for reducing `ordinary disturbances impressed upon the circuit 12, it may be frequently desirable to adjust the phase relationship of the ground currents which, in common with the currents flowing in the track rails, constitute the return flow of the trolley` currents and, in addition thereto, the magnetizing currents of the transformers G.v To accomplish this refined adjustment, the secondary windings' i) and. 10 are each provided with artilicial loads comprising adjustable resistors l5 and adjustable impedance devices 1li. rlhe resistors-l5 and the impedance devices 1li are connected in series relationship with each other, and in shunt to the active turns comprising each secondary winding. The auxil- 1a ry circuits comprising the resistors and the impedance devices correspond to the ground circuit, and the phase and current conditions obtaining within these auxiliary circuits are substantially reproduced in the ground circuit. l

While I have shown and described, in detail, an embodiment of' my invention, it will v be understood by those skilled in the art that many modifications may be lmade without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A system ofvdistribution comprising a source ofeurrent supply, a set of conductors connected to one terminal thereof, a second set of conductors connected to the other terminal, a v`plurality of spaced series transvformers .inductively intel-linking said sets of conductors, each transformer having a single core member and primary windings inserted in serieslcircuit relationship with said first setsofpconductors and Secondary windings inserted in series circuit relationship with said second setv of conductors, and adjustable means to proportion the return current flow in one of said sets of conductors. n j 2. A system of distribution comprising aV source of currentsupply, a plurality of conductors connected to one terminal thereof, a plurality of conductors connected to the other terminal, said ysecond conductors being provided with a plurality of correspondingly spaced insulating joints, a' plurality c j of spaced transformers inductively interlinking all of said conductors with one another, each transformer havinga single core member, primary windings upon which are inserted in series-circuit relationship with said first conductors and secondary windings upon which are connected to said second conductors across v said insulating joints therein, and lmeans to proportion, at will, the return current flow in said second conductors.

3. A railway system comprising a source i of current supply, a plurality of trolley conductors connected thereto, a plurality ofi 13o l.so

' primary windings thereon 'which tracks, spaced transformers to inductively interlink all the tracks with all the trolley conductors; and means serving to ,proportion the current flow in each track.

4. A railway system comprising a source of current supply, a plurality of trolley conductors connected thereto, a plurality of lthe earth, each of conducting rail sectionsinsulated from one another, and spaced transformers having a common core -and primary windings thereon which are connected in series circuit with each trolley conductor and secondary windings which are connected to adjacent rail sections of each track.

5. A rai-lway system comprising a source ofcurrent supply, a plurality of trolley conductors connected thereto, a plurality of tracks in contact which comprises a series of conducting rail sections insulated from one another, spaced transformers having a common core and primary windings thereon which. are connected in series circuit with each trolley conductor and secondary windings which are rconnectedI to adjacent rail sections of each-track, and means serving to proportion the current fiow in each track.

6. A railway system comprising a source of current supply, a plurality of trolley conductors connected thereto, a plurality of tracks in contact with the earth, each of which comprises a series of conducting rail sections insulated from one another', spaced transformers, having a common core and are connected in series circuit with each trolley conductor and secondary windings which *are connected to adjacent rail sections of each with the earth each ofA track, means vserving to proportion the current flow in each track and the earth, and means associated with said secondary windings to adjust the phase relationship of the earth currents.

7. A railway system comprising a source of current supply, a plurality of trolley conductors connected thereto, a plurality of tracks in contact with the earth, each of which coimprises a series of conducting rail sections insulated from olie another, spaced transformers having a commonmore and primary windings thereon which are connected in series circuit with each trolley conductor and secondary windings which are connected to adjacent rail sections of each track, and means serving to proportion the current ioW in each track and the earth.

S. A railway system comprising a source of current supply, a plurality of trolley conductors connected thereto, a plurality of tracks in contact with the earth, each of which comprises a series of conducting rail sections insulated from one another, spaced transformers having a common core and primary windings thereon which are connected in series circuit with each trolley conductor and secondary windings which are connected to adjacent track, means serving to proportion the cur rent How in each track and the earth, and means to adjust the the earth currents.

In testimony whereof, I have hereunto subscribed my name this 23rd day of Dec.

CHAS. F. SCOTT.' lWitnesses:

B. B. HiNEs, M. C. MERz.

rail sections of each phase relationship of 

